The invention relates a gripping device comprising two oppositely placed, spaced gripping elements each having at least one gripping area on a gripping side thereof facing the respective other gripping element, the gripping area of at least one gripping element being able to be pneumatically operated so that in a released position it is further removed from the other opposite gripping surface and in a gripping position it is nearer to the opposite gripping surface.
Such gripping devices have become known under the designation of pneumatic vises for example and are employed for temporary holding of workpieces or articles of many different types. Pneumatic operation has the advantage that gripping and releasing operations may be carried out in quick succession using a source of compressed air under a constant pressure so that there is a constant gripping action for all of a sequence of consecutive gripping operations. A disadvantage has however so far been the fact the gripping surfaces are of a metallic nature so that application is not possible in those cases in which the workpiece or the component to be gripped is prone to be damaged where it is clamped, such damage for instance being in the form of scratches or dents and the like. If the gripping device is for instance to be utilized in conjunction with a lifting device for moving empty or filled cartons in the packaging industry there are likely to be difficulties inasfar as the cartons are not sufficiently stiff in order to oppose the gripping force transmitted by the gripping surfaces. The consequence of this is that the cartons are crushed. Accordingly for such applications vacuum holding devices have been adopted in place of gripping devices of the type in question. However, such suction holding devices are only fully effective if the surfaces of the cartons are quite smooth, and the equipment is not applicable to cartons with a rough surface such as the surface of corrugated board. Since magnetic devices may not be used in this case either, manual labor usually has to be relied upon.